apod wrote:A 30-60% CHO macro seems like it would still produce plenty of TMAO if you're eating choline / carnitine. Although, a high-fat diet low in choline / carnitine seems like a bad idea. Tricky.
Ballantyne points out a paradox that fish is very high in TMAO, but is found to be generally heart healthy. And some folks eat fish and their circulating TMAO is low; for others it's high. So, Ballantyne argues that the increase of good carbs helps sustain a better mix of microbes that either don't produce it in the first place (e.g. increasing Bifidos while likely decreasing Prevotella) or help break down TMAO (e.g. Archaea). See Archaea-related quote at the bottom.
circular wrote:Bitter is supposed to stimulate bile, and a huge problem with the modern industrial diet is a relative lack of bitter foods relative to our ancestors. I wonder if the proverbial ‘early man’ that ate high amounts of animal was compensating for TMAO by ingesting a lot of bitter plant foods that melt the bile flowing.
Bile is an interesting connection here, since it is very connected to microbiota.
Bile Acids and the Gut Microbiome
And Ben Lynch is a proponent of using ox bile and herbal antibiotics for SIBO, because both will help kill off bugs in the SI that shouldn't be there.
So, looks like to me, that bile is also an important part of keeping the right balance of microbiota in the gut.
Archaea: A Microbiome Missing Piece
Archaea degrade TMA and TMAO
One important subtype of archaea are the methanogens, which produce methane gas as a byproduct of hydrogen reduction. Up to 95% of human guts harbor the methanogenic archaea Methanobrevibacter smithii and Methanosphaera stadtmanae, at varying levels. While the idea of producing methane might not sound very pleasant, some of these archaea (in particular, an order of methanogens called the Methanomassiliicoccales) actually play an integral role in reducing our TMAO production. Along with being able to use carbon dioxide, formate, and methanol (all released by bacteria breaking down food and other organic matter in the gut), these archaea can use methyl compounds like TMA and TMAO to generate methane. And that means that the archaea in our gut actually deplete the pool of TMA we have available to be converted into TMAO (along with any free TMAO from foods like seafood). So, all that TMA generated by Prevotella, or entering our body from fish consumption? Archaea can help wipe some of it out!
The TMAO-reducing effects of archaea is far from just speculative, too. In a study of ELDERMET subjects, the fecal TMA concentration in people with TMA-metabolizing archaea was significantly lower than in those without this archaea—and the difference was particularly dramatic when the abundance of Methanomassiliicoccales was greater than 10^8 cells per gram of stool. This role of archaea is so exciting that some scientists are proposing a new class of probiotics called archaeabiotics, which could help reduce our TMAO levels without us needing to cut back on choline and other important nutrients!
Importantly, methanogenic archaea have an important interactive relationship with bacteria in the gut, which often takes the form of what scientists call syntrophy (where two organisms participate in consuming a substance that neither one can catabolize on its own). And, it appears that archaea are particularly chummy with the important probiotic bacteria Bifidobacteria. For example, mixed cultures of M. smithii and Bifidobacteria bifidum have been shown to collectively produce methane from glucose, and in females with gut Methanobacteriales levels higher than 0.71%, there’s a significantly higher mean abundance of Bifidobacteriaceae. And as we’ve already seen, healthy levels of Bifidobacteria are super important!
Archaea Thrive When We Eat Carbs!
So, how do we keep our archaea happy and thriving? Scientists are just at the beginning stages of understanding how diet impacts our archaea colonies (after all, archaea are relative newcomers to the microbiota research scene compared to bacteria!), but here’s what we know so far. In children, organic dairy (especially organic yogurt and organic milk) has been associated with the initial colonization of M. smithii, due to organic dairy serving as a vehicle for delivering it to our guts. And, some methanogens degrade methanol, which gets produced when bacteria degrade pectin in fruits—thus suggesting that archaea might benefit from including fruit in our diets! In Chinese goats, eating a high-grain diet appears to suppress methanogenic archaea relative to a high-hay diet—possibly due to the pH-lowering effect of grains in the rumen (which can then suppress methanogenic archaea that are sensitive to low pH environments). Obviously, we’re not Chinese goats, but it would certainly be interesting if a high-grain diet in humans had a similar effect!
More broadly, though, in humans, Methanobrevibacter abundance is positively associated with higher carbohydrate consumption (both recent and long-term), and negatively associated with recent consumption of fat (especially vegetable fat and polyunsaturated fat intake) and amino acids. Although more research is definitely needed, the picture getting painted so far is that archaea benefit from a variety of plant polysaccharides, and not so much from animal-based diets.
However, this isn’t because the archaea themselves eat carbohydrate. In fact, methanogenic archaea have an almost complete lack of enzymes for breaking down complex carbohydrates into simple sugars. What does appear to be happening is that archaea thrive off the metabolic products of carbohydrate-loving bacteria, and therefore are still dependent on dietary carbohydrate for their own survival!